A contract that, although valid, cannot be enforced by action because it is neither evidenced in writing nor (when this is a permissible alternative) supported by a sufficient act of part performance. Two classes of contracts are involved – guarantees, and contracts for the sale of land entered into before 21 September 1989. By the Statute of Frauds 1677 (in the case of guarantees) and the Law of Property Act 1925 (for land contracts), no contract of either class is enforceable unless its existence and its terms are evidenced by some written note or memorandum signed by the defendant or his agent. By the equitable doctrine of part performance, a land contract entered into before 21 September 1989 (but not a guarantee) can be enforced if, alternatively, the claimant has carried out some act that can be taken as evidencing the existence of the contract. Note that land contracts entered into on or after 21 September 1989 will not even be valid unless they are in writing; the requirement of writing is no longer merely an evidential one.